Method for impregnating stranded cable with waterproofing compound

ABSTRACT

WATERPROOFING COMPOUND AT AMBIENT OR SUBSTANTIALLY AMBIENT TEMPERATURE, IN THE PREFERRED EMBODIMENT, IS CONTINUOUSLY FORCED UNDER PRESSURE TO FLOW THROUGH STAGED CONDUCT SURROUNDING STRANDED CABLE. COMPOUND FILLS INTERSTITIAL SPACES BETWEEN ADJACENT CONDUCTORS IN CABLE AND SIMULTANEOUSLY EXERTS VISCOUS DRAG FORCE ALONG THE SURFACE OF THE CABLE TO PROPEL, OR OTHERWISE CONTROL THE   MOVEMENT OF, THE CABLE. WIPING DIE SUBSEQUENTLY REMOVES EXCESS COMPOUND FROM SURFACE OF CABLE.

May 15, 1973 GQLDMAN ET AL 3,733,216

METHOD FOR IMPREGNATING STRANDED CABLE WITH WATERPROOFIN co UND Filed Apri 9. 71

ill/VENTURE IF? 5. GubD/TiH/v UHHQLJES E. HERE-7D L/ United States Patent METHOD FOR IMPREGNATING STRANDED CABLE WITH WATERPROOFING COMPOUND Ira Bernard Goldman, Levittown, Pa., and Charles Bean Heard, Jr., Lawrenceville, Ga., assignors to Western Electric Company, Incorporated, New York, N.Y.

Filed Apr. 19, 1971, Ser. No. 135,105 Int. Cl. 344d 1/16 US. Cl. 117-231 6 Claims ABSTRACT OF THE DISCLOSURE Waterproofing compound at ambient or substantially ambient temperature, in the preferred embodiment, is continuously forced under pressure to flow through staged conduit surrounding stranded cable. Compound fills interstitial spaces between adjacent conductors in cable and simultaneously exerts viscous drag force along the surface of the cable to propel, or otherwise control the movement of, the cable. Wiping die subsequently removes excess compound from surface of cable.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates, broadly speaking, to a method for impregnating with a compound an elongated element. More specifically, this invention relates to a method for continuously forcing a waterproofing compound, at ambient or substantially ambient temperature in the preferred embodiment, into the interstices of a continuously moving stranded cable.

(2) Description of the prior art Frequently, it is desirable, and even necessary to waterproof stranded cable by applying a waterproofing compound thereto. In order to most elfectively waterproof stranded cable, waterproofing compound should be forced into all of the numerous interstices between adjacent conductors, thereby to fill the said interstices, thus to prevent the entry of water therein. The greater the number of interstices between adjacent conductors, the more difiicult it is to force the waterproofing compound into all the interstices, particularly those interstices remote from the surface of the stranded cable. A typical stranded cable may have as many as 100 conductor pairs, with a very large number of interstices between adjacent conductors. It will be apparent that to fill such large number of interstices with waterproofing compound is a formidable task.

Heretofore, waterproofing compound has been applied while in the liquid state and at nominal pressures to stranded cable. There are several problems that has arisen in the practice of the conventional method:

(1) Inasmuch as the waterproofing compound has been heated above its melt temperature, which may be as high as 230 F., for example, contact of the hot Waterproofing compound with the insulation on the conductors has caused degradation of the insulation.

(2) The heated waterproofing compound, after application to the stranded cable, may retain significant heat for as long as hours, and such retained heat may adversely aifect filler materials conventionally employed in the waterproofing compound to enhance certain electrical properties thereof.

(3) The waterproofing compound shrinks as it cools from elevated temperature to ambient temperature, and voids are created.

(4) There are limits as to the percentage of fill of interstitial space with waterproofing compound attainable by the conventional method, particularly in th larger cables with heavier gauge conductors.

3,733,216 Patented May 15,, 1973 SUMMARY OF THE INVENTION On of the objects of this invention is to provide an improved method for impregnating with a compound an elongated element.

Another of the objects of this invention is to provide an improved method of continuously impregnating a stranded element with a compound.

A further object of this invention is to provide an improved method for continuously and effectively filling with a waterproofing compound at ambient or substantially ambient temperatures interstitial spaces between conductors of a continuously moving stranded cable.

Yet other and further objects of the present invention will become apparent during the course of the following description and by reference to the accompanying drawing and the appended claims.

Briefly, we have discovered that the foregoing objects may be attained by introducing, at ambient or substantially ambient temperature in the preferred embodiment, and under pressure waterproofing compound into the annular space between the stranded cable and a surrounding conduit, whereby the compound exerts a viscous drag force along the surface of the stranded cable to continuously propel, or otherwise control the movement of, the cable through the conduit and simultaneously, the waterproofing compound is forced into the interstices of the cable under pressure thereby to fill said interstices. There may be several stages, operating under different pressures, in the conduit, in which the waterproofing compound is employed to propel the cable and simultaneously to fill the interstices.

BRIEF DESCRIPTION OF THE DRAWING Referring now to the drawing, in which like numerals represent like parts in the several views:

FIG. 1 represents a partially diagrammatic view of a system for practicing the method of the present invention, showing in medial longitudinal section a preferred embodiment of the viscous drag apparatus through which a stranded cable is propelled and filled with waterproofing compound;

FIG. 2 represents a transverse section taken along the line 22 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A system for practicing the method of the present invention is seen as comprising viscous drag apparatus 1, through which stranded cable 2 is, in the preferred embodiment, propelled and filled with water-proofing compound 3, wiping die 4, pump 5 and supply tank 6.

Viscous drag apparatus 1 comprises hOusing 7 having axially aligned longitudinal bores 8 and 9 extending inwardly from the opposite ends thereof, the said bores 8 and 9 terminating .at partition Wall 10. Bushing 11 is mounted through partition wall 10 on the same axis as longitudinal bores 8 and 9 and is adapted to slidably receive, with close clearance, stranded cable 2. End closures 12, each with a bushing 13 axially aligned With the adjacent longitudinal bore 8 or 9 and adapted to slidably receive with close clearance stranded cable 2, are mounted to the ends of housing 7 within counterbores 14, and are suitably secured to said housing 7 against outward movement therefrom by suitable means, such as, for example, bolts 15 spaced around the peripheral portion of such end closures 12 and extending therethrough and threaded into the said housing 7.

It will be seen from the foregoing that a path, bounded by bushings 13 and 11 and longitudinal bores 8 and 9,

extends through housing 7, and stranded cable 2 is adapted to pass along this path. Moreover, it will be seen that the diameters of longitudinal bores 8 and 9 are somewhat larger than the diameter of stranded cable 2. The longitudinal axis of stranded cable 2 is aligned with the longittudinal axis of bores 8 and 9 and the spaces between bores 8 and 9 and the stranded cable 2 define chambers in which water proofing compound 3 acts, as hereinafter described, to propel stranded cable 2 and to fill the interstices therein.

Transverse bores 16 and 17 extend through housing 7 and communicate with the rear and forward ends respectively of longitudinal bore 8, with reference to the direction of movement of stranded cable 2 through viscous drag apparatus 1. Similarly, transverse bores 18 and 19 extend through housing 7 and communicate with the rear and forward ends respectively of longitudinal bore 9 with reference to the direction of movement of stranded cable 2 through viscous drag apparatus 1.

Conduit 20 communicates between the discharge of pump and transverse bore 16. Conduit 21 communicates between transverse bore 17 and transverse bore 18. Conduit 22 communicates between transverse bore 19 and supply tank 6. Conduit 23 communicates between supply tank 6 and the intake of pump 5. Supply tank 6 is replenished, as required, with waterproofing compound 3 through conduit 24.

Pump 5 is adapted to draw waterproofing compound 3, at ambient or substantially ambient temperature in the preferred embodiment, from supply tank 6 and to force said compound 3, under pressures which may, for example, be 1000 p.s.i., through conduit 20 and transverse bore 16 to the rear of longitudinal bore 8. Waterproofing compound 3 will travel from the rear to the forward end of longtudinal bore 8 (i.e., from right to left as viewed in FIG. 1) and will exit through transverse bore 17. While flowing through the chamber defined by the space between bore 8 and stranded cable 2, in an overall general direc tion which is parallel to the longitudinal axis of stranded cable 2, the pressurized waterproofing compound 3 will force its way into the interstices between adjacent conductors of the stranded cable 2. At the same time, the flowing waterproofing compound 3 will exert a viscous drag force along the surface of the stranded cable 2, which viscous drag force propels the stranded cable 2 toward the forward end of longitudinal bore 8. Thus, the waterproofing compound 3, simultaneously :fills the interstices in the stranded cable 2 and propels the stranded cable 2.

Similarly, the waterproofing compound 3 which exits from the forward end of longitudinal bore 8 enters the rear of longitudinal bore 9 through transverse bore 18 and flows toward the forward end of longitudinal bore 9, exiting through transverse bore 19. While flowing through the chamber defined by the space between longitudinal bore 9 and stranded cable 2, the pressurized waterproofing compound 3 will force its way into the interstices between adjacent conductors of the stranded cable 2 and, at the same time, the flowing waterproofing compound 3 will exert viscous drag force along the surface of the stranded cable 2 toward the forward end of longitudinal bore 9, which viscous drag force propels the stranded cable 2 toward the forward end of longitudinal bore 9. Bushings 11 and 13 are designed to prevent escape of the pressurized waterproofing compounds 3 from the ends of the chamber respectively defined by longitudinal bores 8 and 9 and stranded cable 2.

It will be seen that two stages are provided in which the stranded cable 2 is propelled by the viscous drag force exerted by the flowing waterproofing compound 3 and simultaneously is filled (in the interstitial spaces between adjacent conductors) by the pressurized waterproofing compound 3. It will also be seen that the first stage (viz, in the space defined by longitudinal bore 9 and stranded cable 2) operates at a somewhat lower pressure due to pressure drop along the path of the flowing waterproofing compound 3, than the second stage (viz, in the space defined by longitudinal bore 8 and stranded cable 2). This arrangement has been found to yield exceptionally good results. Under various circumstances, only one stage may be required to satisfactorily fill the interstices in a stranded cable 2, and under other circumstances, more than the two stages herein shown my be required, in which event the stages would be aligned in order of ascending pressures from the rear to the forward end of the viscous drag apparatus 1 (i.e., with these stages, transverse bore 19 would communicate through a suitable conduit with the rear of a third stage, and conduit 22 would communicate with the forward end of said third conduit). Alternatively, each stage could be provided with its own pump 5 and supply tank 6.

The operation of the present invention will be apparent from the foregoing description. Briefly, stranded cable 2 is threaded through viscous drag apparatus 1 and wiping die 4. Pump 5 is started, and waterproofing compound 3 is forced along the hereinbefore described path. The viscous drag force of the flowing waterproofing compound 3 exerted along the surface of the stranded cable 2 draws the stranded cable 2 through the viscous drag apparatus 1, the interstices of the said stranded cable 2 being filled with the pressurized waterproofing compound 3 in the two stages specifically shown herein. As the filled stranded cable 2 passes through wiping die 4, a suitable mechanism (such as an elastomeric apertured diaphragm, not shown) within the wiping die 4 removes excess waterproofing compound 3 from the surface of the stranded cable 2.

It will be apparent, from the foregoing, that in the preferred embodiment of the invention, the viscous drag force exerted by the waterproofing compound is employed to propel the stranded cable 2. It should be clearly understood that such viscous drag force may also be employed, in alternative embodiments, to control the movement of a stranded cable which is propelled by other means external to the viscous drag apparatus 1. Thus, such viscous drag force may be exerted on the stranded cable 2 in a direction opposed to the direction of movement of said stranded cable 2 thereby to retard such movement and thereby act as a brake. Conversely, such viscous drag force may be employed to augment the propulsion of stranded cable 2 by other means. Generally, then, the viscous drag force may be employed to propel stranded cable 2 or to control the movement of stranded cable 2.

What is claimed is:

1. Method for filling with material the interstices between adjacent strands of a stranded cable adapted to be moved through an upstream station and thereafter through a downstream station, said method comprising:

(a) producing an upstream fiow of pressurized material;

(b) applying said upstream flow of pressurized material at an upstream station along and in contact with the entire peripheral surface of said stranded cable as the said stranded cable is moved through the said upstream station, said upstream flow of pressurized material exerting viscous drag force along the surface of said stranded cable;

(c) producing a downstream flow of pressurized material;

(d) applying said downstream flow of pressurized material at a downstream station along and in contact with the entire peripheral surface of said stranded cable as the said stranded cable is moved through the said downstream station, said downstream flow of pressurized material exerting viscous drag force along the surface of said stranded cable;

(e) moving said stranded cable through the upstream station and thence through the downstream station under the influence of said viscous drag forces;

(f) the average pressure of said upstream flow at said upstream station being lower than the average pressure of said downstream flow at said downstream station;

(g) said pressurized material filling interstices between adjacent strands of said stranded cable at said upstream and downstream stations;

(h) adding make-up material to the flows of pressurize material to replace that material which has entered the interstices in said stranded cable.

2. Method as in claim 1, further comprising:

(i) applying said flows of pressurized material along the surface of the stranded cable in the direction of movement thereof thereby to apply said viscous drag forces to propel said stranded cable through the upstream station and thence through the downstream station.

3. Method as in claim 1, further comprising:

stream station and thence through the downstream station,

(j) applying said flows of pressurized material along the surface of said stranded cable opposite to the direction of movement thereof thereby to apply said viscous drag forces to retard movement of said stranded cable through said upstream and downstream stations.

4. Method as in claim 1, wherein:

(i) said material is at substantially ambient temperature.

5. Method for filling with material the interstices between adjacent strands of a stranded cable adapted to be moved through an upstream station and thereafter through a downstream station, said method comprising:

(a) producing a flow of pressurized material;

(in) applying said flow of pressurized material from the upstream end to the downstream end of a downstream station and thence from the upstream end to 6 the downstream end of an upstream station, said flow of pressurized fluid running along and in contact with the entire peripheral surface of the stranded cable and exerting viscous drag force along the surface of the stranded cable to propel the said cable through the upstream station and thence through the downstream station;

(c) the average pressure of said flow at said upstream station being lower than the average pressure of said flow at said downstream station;

((1) said pressurized material filling interstices between adjacent strands of said stranded cable at said upstream and downstream stations;

(e) adding make-up material to the flow of pressurized material to replace that material which has entered the interstices in said stranded cable.

6. Method as in claim 5, wherein:

(f) said material is at substantially ambient temperature.

References Cited UNITED STATES PATENTS 2,393,678 1/1946 Graham 118405 1,681,566 8/1928 Anderegg 118DIG. 18 3,122,786 3/1964 Huisman 118408 X 2,390,823 12/1945 Bennett 118405 X 1,845,116 2/1932 Apple 117128 3,672,974 6/ 1972 Tomlinson 1l7115 3,667,267 6/1972 Fuchs 72-60 RALPH S. KENDALL, Primary Examiner US. Cl. X.R. 

